[Warner306]

It generally isn't advised to use a 3D LUT for the HDR mode of LG OLEDs. They aren't very accurate compared to SDR 3D LUTs due to the display's tone mapping. You will end up with a lot of luminance and saturation errors.

You can create an HDR 3D LUT with DisplayCal, but I'm not familiar with the workflow and this will only create a single static tone curve for the display for all sources. So you could possibly create several static tone curves to handle sources with different mastered peak nits. You would have to do some searching on the DisplayCal forums to find the correct settings parameters if you wanted to experiment with these type of LUTs.

The built-in CalMAN AutoCal feature of the LG OLEDs would likely produce better results, but you must first purchase a copy of CalMAN.

If you want to calibrate the display's HDR mode, you are usually better off by adjusting the grayscale manually with HCFR. Don't touch the brightness or contrast controls in HDR mode because they are set by default to optimize the display's tone mapping. Some calibrators will only use the RGB high and low controls to calibrate HDR mode and others will use the full 10-20 point white balance controls. It would be safest to start with the RGB high and low controls to see how much of an improvement can be made. The rest of the calibration process is the same as SDR mode.